Glyptocrinus Redefined and festricted, etc. 229 
subradial, which bears an additional depressed semi-cylindrical ridge 
extending upward to the superior truncated side. Primary radials, 
three in each series, except the left posterior ray which has only two. 
The first and last are pentagonal, and of almost the same size, form 
and ornamentation, so that by reversing ends they would nearly fill 
each other’s places. Secondary radials, twelve to about sixteen in 
each series. ‘The second one gives offa ridge that strengthens the 
interradial areas. Azygous area covered by more than fifty plates, 
the middle row being larger and more prominent than the others up 
to about the sixth plate. Arms, twenty. Pinnules long, 
It occurs in the upper part of the Hudson River Group. 
Gaurocrinus coenatus (S. A. Miller). 
G. cognatus is distinguished from G. nealli, by its more robust 
form, the plates of the radial series are proportionally larger, and 
those of the interradial and intersecondary radial areas larger and 
less numerous. The radial ridges are not so prominent. 
Only part of the head of this species is known, but it may be easily 
distinguished. 
It occurs in the upper part of the Hudson River Group. 
GAUROCRINUS ANGULARIS (S. A. Miller). 
The depression of the interradial spaces gives to this species a strong 
angular outline, which is increased by the downward extension of the 
subradials below the junction of the column with the body. Radial 
ridges strong. Basals showing upon the exterior a low triangular out- 
line. Subradials slightly longer than wide, and having a ridge which 
extends below into a cuneiform tubercle, and bifurcates above, sending 
a ridge to each of the adjoining radials. Primary radials three by 
five. Secondary radials two by ten, ‘Tertiary radials three or four by 
twenty. Interradials twelve or thirteen to the top of the second 
secondary radials. Two or three intersecondary radials in each series 
following each other in line. The central row of plates in the azygous 
area are large, and slowly diminish in size before they are lost in the 
plates of the vault. 
This is the same species described under the name of Keteocrinus 
gractlis, by Prof. Wetherby, some time after it had been described and 
illustrated as G. angularis. 
It uvccurs in the middle part of the Hudsou River Group. 
